Identification of problem foods using food and symptom diaries.

Food and symptom diaries were used to identify problem foods for each of 164 patients with chronic medical problems such as headache, fatigue, congestion, abdominal pain, and sinus problems. A statistical analysis related the total load of 90 biologic families, as well as caffeine, alcohol, and lactose, to changes in symptom intensity during a 2-week diary. The results helped 75% of the patients when used as a guide for elimination diets. Open challenges confirmed 47% of the identified food components. This study required a database and software to estimate recipe components for an average of 243 foods per patient. The analysis of each patient's diary produces a main report that lists suspect food components for each symptom. The report lists components in decreasing order of statistical confidence and gives lag times between food ingestion and symptom change. This report also shows that initial direction of the symptom change as a direct or masking effect. Foods that appear "safe" or unrelated to the symptoms are also listed. A second report lists the patient's food sources for each of the suspected food components. The report shows the percentage contribution of source foods and is useful for patient education and the design of elimination diets.